JP2002266770A - Bistable pump and hydraulic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a hydraulic device including a control device controlling the speed and the force of an operating state by varying a motor rotation speed and pump capacity and to provide a liquid pump suited thereto. SOLUTION: In a variable displacement hydraulic pump 5, a pump capacity is changed over to either the upper limit or the lower limit of a variable capacity range. Thereby, the pump 5 becomes a bistable pump and control conditions can be narrowed so as to simplify a control means. The changeover is performed by a directional control valve 5b concerned to a variable capacity mechanism 5a. The lower limit of the variable capacity range is set to be adjustable 5j. A mitigating means 5k lowering the changeover speed from the upper limit to the lower limit is also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic device such as a hydraulic device for driving a liquid pump for supplying a pressurized liquid to an operating portion by an electric motor. And a hydraulic device for selectively performing the following. The present invention also relates to a variable displacement type liquid pump suitable for incorporation into such a hydraulic device, and more particularly, to a liquid pump in which the pump displacement is stabilized at either the upper limit or the lower limit of the displacement range depending on the switching state. It also refers to a bistable pump.

[0002]

2. Description of the Related Art In some hydraulic devices, when driving a working part such as a hydraulic actuator, a movable member such as a rod reaches an operation limit such as a cylinder end and the operating force is rapidly increased. It is sometimes convenient to automatically switch from control to force control.For this purpose, a speed detection means and a pressure detection means are provided, and the detection result is fed back so that the detected speed follows the speed command. There is a configuration in which one of force control for following a detected pressure is selected and made valid.

Recently, hybrid systems for driving a constant displacement hydraulic pump with a servomotor have been increasing as hydraulic devices for performing such control because of advantages such as low energy consumption and easy miniaturization of an electric motor. In addition, it has advantages such as easy control such as speed control and pressure control that follow the control command, so that variable displacement hydraulic pumps can be driven by servo motors and variable displacement hydraulic pumps can be used. A motor driven by a variable speed brushless DC-DC motor has also been proposed.

[0004]

In such a hydraulic device, a wide controllable range combining the controllable range of the electric motor and the controllable range of the liquid pump is used. If control conditions are appropriate, it is theoretically expected that optimization such as improvement of energy efficiency will be achieved. However, in a situation where the controllable range is large and the number of control variables and the like is large, it is generally not simple to determine the optimal control conditions and the like, and a complicated design work and complicated operation confirmation are required. For this reason, in a situation where the operating conditions change greatly or a situation where it is required to quickly provide one that is suitable for various applications, the control means is complicated, and the design and development burdens are heavy. It is.

Therefore, it is necessary to adopt a combination of the speed control of the electric motor and the displacement control of the liquid pump, and to make the control means simple and simple even in such a case. The present invention has been made in order to solve such problems, and a hydraulic device that performs speed control and force control in an operating state by varying a motor rotation speed and a pump capacity, including a control unit, is simply provided. It is intended to be realized. Another object of the present invention is to realize a liquid pump suitable for being incorporated in such a hydraulic device.

[0006]

Means for Solving the Problems First to fourth solving means invented to solve such problems are as follows.
The configuration and operation and effect will be described below.

[First Solution] A bistable pump according to a first solution is a variable displacement type liquid pump as described in claim 1 at the beginning of the filing application, which is one of an upper limit and a lower limit of a variable capacity range. Is provided with a switching means for switching the pump capacity. Further, as a first solution of the present invention, a hydraulic device incorporating such a bistable pump is provided with the above-mentioned bistable pump, an electric motor for driving the same, and the aforementioned bistable pump. An operation unit that receives supply of pressure liquid from the stable pump, a first detection unit that detects a physical flow amount corresponding to a discharge flow rate of the bistable pump or a speed of a movable member of the operation unit corresponding thereto, and a first control amount. A first control amount calculating unit configured to generate the first control amount such that a detection value of the first detection unit is made to follow a received or generated first control command, if provided for rotation control of the electric motor; A second detecting means for detecting a discharge pressure of the liquid pump or a force generated in the operating portion in response thereto;
If the control amount is used for controlling the rotation of the electric motor, a second control amount calculation for generating the second control amount such that the detection value of the second detection means follows the received or generated second control command. Means, selecting means for selecting one of the first control amount and the second control amount for rotation control of the electric motor, and switching operating means for operating the switching means in response to the selection It is provided with.

[0008] In the hydraulic device of the first solution incorporating the bistable pump of the first solution, when the bistable pump, which is a liquid pump, is driven by the electric motor, the device is actuated from the bistable pump. The pressurized liquid is supplied to the section, and the movable section is driven in the operating section. Further, when the speed or the like is detected by the first detecting means, and the first control amount generated by the first control amount calculating means based on the detected value is provided to the rotation control of the electric motor by the selecting means, The speed or the like of the movable member follows a first control command such as a command, and speed control is performed. Further, a force such as a discharge pressure of the liquid pump or a thrust of the movable member is detected by the second detecting means, and a second control amount generated by the second control amount calculating means based on the detected value is selected by the electric motor by the selecting means. , The discharge pressure and the like follow the second control command such as the pressure command, and the force control is performed. Thus, the speed control and the force control are selectively performed based on the rotation control and the like of the electric motor.

Further, in response to the selection, that is, when the speed control in which the first control amount is selected or in the force control in which the second control amount is selected, the switching means switches the switching means. It is activated and the pump displacement is switched accordingly. That is, in the bistable pump, the pump displacement becomes the upper limit of the displacement range during the speed control, and the pump displacement becomes the lower limit of the displacement range during the force control. In this way, the basic pumping capacity of the liquid pump is increased during speed control that requires a large flow rate, while the basic pumping capacity of the liquid pump is suppressed when controlling a small amount of force, so that the supply of excessive pressure liquid is avoided. Energy consumption is reduced.

Moreover, the liquid pump is a simple bistable pump which can be realized by adding a switching means to the variable displacement pump, and the control is switched only in accordance with the selection between the speed control and the force control. , By simple means. Even in such a case, as described above, the speed control and the force control are performed based on the feedback control with respect to the rotation control of the electric motor.

As described above, on the premise that the speed control and the force control in the operating state are selectively performed, when changing the motor rotation speed and the pump capacity, the change of the pump capacity is performed simply by changing the capacity of the bistable pump. Since the control conditions are narrowed down without any inconvenience in operation by performing such a method, the setting of the optimum conditions and the like are simplified, and the control means is also simplified. Therefore, according to the present invention, it is possible to easily realize a hydraulic device or the like including the control means for selectively performing the speed control and the force control in the operating state by changing the motor rotation speed and the pump displacement.

[Second Solution] A bistable pump according to a second solution of the present invention is, as described in claim 2 of the present application, a pump main body driven to rotate and suck and discharge a liquid, and a unit rotation thereof. A variable displacement mechanism for varying the discharge capacity per unit, and a high pressure side flow path such as a discharge pressure and a low pressure side flow path such as a suction pressure connected to a pressure guiding path communicating with a pressure receiving portion of the variable capacity mechanism. And a switching valve for communication.
The hydraulic device of the second solution incorporating such a bistable pump is as described in claim 5 at the beginning of the application.
A bistable pump according to the second solving means, the electric motor, a rotation control means thereof, the operating section, the first detecting means, the first control amount calculating means, the second detecting means, The apparatus comprises the second control amount calculating means, the selecting means, and a switching operating means for operating the switching valve in response to the selection.

[0013] In the bistable pump according to the second solution, the high pressure side flow path and the low pressure side flow path are connected to the pressure guide path communicating with the pressure receiving portion of the variable capacity mechanism in accordance with the operation state of the switching valve. When one of the flow paths is connected, the pump capacity by the capacity variable mechanism increases or decreases and settles at either the upper limit or the lower limit of the capacity variable range. Thus, the bistable pump and the hydraulic device according to the first solving means described above are realized.

In addition, since the switching means, which is the main point, is embodied by the switching valve introduced to the pressure guiding path involved in the variable capacity mechanism, the troublesome remodeling of the mechanical and mechanical parts is not possible. It is possible to use only the pump, and only a part of the additional mechanism, so that the operation can be performed more easily. Therefore, according to the present invention, it is possible to more easily realize a hydraulic device or the like including the control means for selectively performing the speed control and the force control in the operating state by varying the motor rotation speed and the pump displacement.

[Third Solution] The bistable pump according to the third solution is the bistable pump according to the first solution, as described in claim 3 of the present application. There is provided a lower limit adjusting means capable of adjusting a lower limit of the capacity variable range in the solution means or a lower limit of the capacity variable range by the capacity variable mechanism in the second solution means. Further, the hydraulic device of the third solution means is such that the bistable pump of the third solution means is incorporated in the hydraulic device of the first and second solution means as described in claim 5 at the beginning of the application. It is.

If the lower limit of the variable capacity range is zero or close to zero as in a general variable displacement pump, the required flow rate may be small even if the discharge flow rate is small at the time of force control in which the pump capacity is at its lower limit. Since the electric motor or the liquid pump must rotate at a high speed to secure this, the mechanical efficiency of the electric motor or the like tends to decrease.
In the bistable pump and the hydraulic device of the solution of the above, since the lower limit of the variable capacity range can be adjusted, by adjusting it to be zero or larger than substantially zero, the electric motor or the liquid at the time of force control is adjusted. It is possible to reduce the rotation state of the pump.

Thus, the mechanical efficiency during force control is improved. Moreover, it can be easily performed by adjusting the amount of adjustment. Therefore, according to the present invention, a simple hydraulic device or the like including a control unit can be used to perform the force control even when the speed control and the force control in the operating state are selectively performed by changing the motor rotation speed and the pump displacement. A decrease in mechanical efficiency at the time can also be easily prevented.

[Fourth Solution] The bistable pump according to the fourth solution is the bistable pump according to the third solution, as described in claim 4 of the present application. The present invention further comprises a switching mitigation means for lowering the switching speed when switching from the upper limit to the lower limit of the variable capacity range performed by the switching means in the solving means or the switching valve in the second solving means. Further, the hydraulic device of the fourth solution means is as described in claim 5 at the beginning of the application.
The bistable pump of the fourth solution is incorporated in the hydraulic device of the first to third solutions.

In the bistable pump and the hydraulic device according to the fourth solution, when the control of the operating state of the operating unit is switched from the speed control to the force control, the pump capacity is correspondingly changed. The displacement is switched from the upper limit to the lower limit of the variable capacity range. However, since the switching speed is reduced by the switching relaxation means, the pump discharge flow rate is gently reduced. This, coupled with the fact that the lower limit of the variable capacity range is adjusted to be greater than zero, causes the liquid supply state by the pump to suddenly change beyond the acceleration performance of the electric motor or the like when switching from speed control to force control. This is reliably prevented, so that even if the pump displacement is simply changed in conjunction with switching from speed control to force control, there will be no pressure fluctuation or the like accompanied by an undesired impact. Therefore, according to the present invention, a simple hydraulic device or the like including a control unit can be used to perform the force control even when the speed control and the force control in the operating state are selectively performed by changing the motor rotation speed and the pump displacement. In addition to easily preventing the mechanical efficiency from being lowered at the time, it is also possible to prevent the occurrence of an impact or the like when switching from speed control to force control.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION With respect to the bistable pump and the hydraulic device of the present invention achieved by such a solution, specific embodiments for implementing the same will be described with reference to the following first to third embodiments. explain. The first embodiment shown in FIGS. 1 to 3 embodies the first to fourth solving means described above.
The second embodiment shown in FIGS. 4 and 5 and the third embodiment of FIG. 6 are modifications thereof. In these drawings, for simplification and the like, a housing panel, a fastener such as a base, a frame, and a bolt, a connector such as a hinge, a seal member such as an O-ring, and a connection member such as a joint are illustrated. Omit,
Signs and blocks are mainly used to illustrate and relate to those necessary for the description of the invention. The electric signal line and the hydraulic main line are shown by thin solid lines, and the hydraulic pilot line is shown by a thin long broken line.

[0021]

First Embodiment A first embodiment of a bistable pump and a hydraulic device according to the present invention will be described with reference to the drawings. 1 shows a pump structure and the like, (a) is a detailed block diagram, (b) is a pressure-flow rate characteristic graph when rotated at a constant speed, and (c) shows a principle of a variable capacity system using a swash plate. FIG. 3D is a perspective view of a main part, and FIG. 4D is a cross-sectional view of the main part to which a variable displacement mechanism, a switching valve, and the like are added. 2A and 2B show the configuration of the hydraulic device, wherein FIG. 2A is an overall block diagram, and FIG. 2B is a block diagram of a motor controller. Further, FIG.
FIG. 3 is a circuit diagram of a motor driver. First, the liquid pump 5 (bistable pump) will be described, and then a hydraulic device incorporating the same will be described.

As the liquid pump 5 (see FIG. 1), an axial piston pump capable of variably controlling the tilt angle of the swash plate 5h is often used. However, if the pump is of a variable displacement type, another axial piston pump such as a radial piston pump or a vane pump is used. It may be of type. In any case, a pump body that rotates and drives the pump shaft 5d to suck and discharge liquid is provided with a capacity variable mechanism 5a that varies the discharge capacity per unit rotation. If the movable range of the swash plate 5h is not restricted, when the capacity of the liquid pump 5 reaches the upper limit of the controllable range, the maximum amount is discharged per unit rotation speed of the pump shaft 5d, and the capacity of the liquid pump 5 is controlled. When the lower limit is reached, the discharge amount Q becomes substantially zero.

If an axial piston pump is used as an example (see FIGS. 1 (c) and 1 (d)), when the cylinder block 5f is driven to rotate by the electric motor 4 via the pump shaft 5d, one end is attached to the shoe plate 5g. Are moved forward and backward, whereby the liquid such as oil is sucked from the suction port 5e of the valve plate and the liquid is discharged from the discharge port 5c of the valve plate. . A swash plate 5h (yoke) that defines the inclination of the shoe plate 5g is supported so as to be capable of tilting, and the tilt is variably controlled by a variable capacity mechanism 5a. The variable capacity mechanism 5a includes a swash plate 5h.
And a pressure receiving member capable of moving forward and backward while pressing the guide valve. The pilot pressure supplied to the pressure guiding path 5i is guided to the pressure receiving member through an appropriate communication path. If the pilot pressure is high, the swash plate 5h tilts. By changing the turning angle, the stroke of the piston and the discharge flow rate Q approach zero, and when the pilot pressure is low, the swash plate 5
By changing the tilt angle of h in the opposite direction, the stroke of the piston and the discharge flow rate Q are made close to the maximum.

(See FIGS. 1 (a) and 1 (d).) Further, a switching valve 5b (switching means) is also attached to the pump body so that one of the ports is aligned with the end of the pressure guiding path 5i. Switching valve 5b
Is a switching signal A from the motor controller 20 described later.
The solenoid valve is a two-position solenoid valve which operates in accordance with the following. Each port has a high-pressure side flow path communicating with the discharge port 5c of the pump and guiding the discharge pressure P, in addition to the pressure guide path 5i. A low-pressure side flow path that communicates with the suction port 5e and guides a suction pressure of atmospheric pressure or lower than that is also connected to communicate with the suction port 5e. When the switching signal A is off, the pressure guiding path 5i is communicated with the low pressure side flow path, thereby switching the pump capacity to the upper limit of the variable capacity range by the variable capacity mechanism 5a (see the solid line graph in FIG. 1B). Switching signal A)
Is turned on, the pressure guiding passage 5i is communicated with the high-pressure side flow path, thereby switching the pump capacity to the lower limit of the variable capacity range by the variable capacity mechanism 5a (the long dashed line graph in FIG. 1B). reference).

Further, (see FIGS. 1 (a) and 1 (d)), in order to make the lower limit adjustable, a contact position adjusting screw mechanism 5j (lower limit) is provided in the pump body where it interferes with the variable capacity mechanism 5a. Adjustment means) is also provided. The contact position adjusting screw mechanism 5j is provided on the side opposite to the pressure receiving member with respect to the swash plate 5h, and restricts the movable range of the swash plate 5h from the lower limit side by the tip of the screw member abutting on the swash plate 5h. It is supposed to. The screw member is provided so as to penetrate the casing, and is also provided with a lock nut, a suitable seal member (not shown), and the like. Then, when the exposed end is turned with a suitable jig or the like, the screw member advances and retreats toward the swash plate 5h, so that the lower limit stop position of the swash plate 5h can be changed. Thereby, the lower limit of the variable capacity range by the variable capacity mechanism 5a can be adjusted from outside (FIG. 1).
(See (b) the long broken line graph, the short broken line graph, and the dotted line graph).

The switching valve 5b is also provided with a throttle 5k (switch relaxation means) composed of a male screw member having an orifice or a choke-shaped small hole formed therethrough. This aperture 5k
Is screwed deep into a port communicating with the high-pressure side flow path, and when the switching signal A is turned on, the discharge port 5c
The flow rate of the liquid flowing into i is regulated to a small amount. Then, based on the flow rate regulation, the pilot pressure to the variable capacity mechanism 5a is slowly increased when increasing from the suction pressure to the discharge pressure P, and the pressure receiving member receiving the pilot pressure is also moved slowly, so that the capacity of the switching valve 5b is increased. When switching from the upper limit to the lower limit of the variable range, the switching speed is reduced. The throttle 5k is connected to the switching valve 5b by the pump body.
Can be easily replaced with a screwdriver such as a wrench, which makes it easy to change the amount of throttle such as the orifice diameter, etc.
The switching speed may be reduced by, for example, making a taper or notch at the edge of the spool of the switching valve 5b.

Next, a hydraulic device incorporating the above-described liquid pump 5 (see FIG. 2A)
(Control means) performs sequence control corresponding to an application while issuing control commands to some drive systems. One of the drive systems is to drive the liquid pump 5 with the electric motor 4. Has been adopted. An operating unit 6 including a hydraulic actuator or the like is connected to the discharge side of the liquid pump 5 via a pipe such as a rubber hose or a metal pipe so as to be hydraulically drivable, and is used to drive a movable member of the operating unit 6. The necessary pressure liquid is supplied from the liquid pump 5 to the operation unit 5.

A typical example of the operating section 6 is a hydraulic cylinder. In this case, the movable member is a liquid pump 5
The operation limit 6a is a cylinder end where the rod abuts, or a filling of the mold into the mold at the tip of the rod. Or In order to detect the moving speed of the movable member, the operating section 6 includes a speed detecting means 6b.
(First detecting means) is additionally provided. The speed detecting means 6b detects the speed Vf (detected value of the first detecting means) of the movable member using an appropriate detecting device such as a rotary encoder or a linear encoder. In addition, an element to be detected such as a magnet may be provided, or a notch for passing detection light may be formed. The discharge pressure P of the liquid pump 5 is provided in a pipe or the like between the operating section 6 and the liquid pump 5.
Is detected, a force detecting means 6c (second detecting means) is connected. For this purpose, a pressure gauge with a piezoelectric conversion circuit or the like is employed to feed back the detected pressure Pf (the value detected by the second detecting means) as an electric signal.

Further, a servomotor capable of at least current control and torque control is adopted as the electric motor 4,
The motor control electronic circuit 2 is connected so that a drive current can be supplied thereto. In order to enable current control / torque control between the electric motor 4 and the motor control electronic circuit 2, the drive current is detected and converted to an electric signal (If) and fed back to the motor control electronic circuit 2. A current detecting means 4a is provided. The motor control electronic circuit 2 receiving the feedback signal is connected to the main controller 1 so as to be able to transmit and receive the signal.
Receives the speed command Vc (first control command) generated in step (1) and performs speed control based on the received speed command Vc. The pressure command Pc (second control command) also generated by the main controller 1
In response, pressure control (force control) is performed.

Therefore, the motor control electronic circuit 2 includes:
A motor driver 30 having a power transistor or the like to generate a drive current for the electric motor 4, and a three-phase pulse signal Up, for example, for controlling on / off of the power transistor in association with each phase of the electric motor 4. Vp, Wp
And a motor controller 20 that generates the data and sends the generated data to the motor driver 30. The rotation of the electric motor 4 by the motor controller 20 is controlled by the drive current If
The speed control and the pressure control by the motor controller 20 are performed in multiple feedback loops including the current control as a minor loop.

The motor controller 20 (see FIG. 2B) is embodied by any one of a dedicated analog circuit, a digital circuit, a general-purpose microprocessor system, or the like, or a combination thereof. 4a, the speed detection means 6b
The speed Vf and the pressure Pf from the force detecting means 6c are also fed back via appropriate signal transmission cables and the like. The motor controller 20 is provided with first control amount calculating means 21 + 22 for generating a speed control amount Vp (first control amount) from the speed command Vc and the speed Vf in order to perform speed control. In order to perform the current control, a second control amount calculating means 23 + 24 for generating a pressure control amount Pp (second control amount) from the pressure command Pc and the pressure Pf is provided. Is provided.

The first control amount calculating means 21 + 22 sends the speed control amount Vp as the current command Ip to the motor rotation control means 2 + 22.
In order to generate a speed control amount Vp that causes the speed Vf to follow the speed command Vc when transmitted to 7 + 28, that is, to generate a speed control amount Vp such that the speed Vf approaches and matches the speed command Vc. Speed command V
and a speed error calculating unit 21 such as a subtraction circuit for calculating the difference ΔV by subtracting the speed Vf from the speed c.
A speed control amount calculation unit 22 is also provided that performs appropriate amplification, integration, and other processing on V to generate a speed control amount Vp.

The second control amount calculating means 23 + 24 receives the pressure control amount Pp as the current command Ip and outputs the current command Ip.
In order to generate a pressure control amount Pp that causes the pressure Pf to follow the pressure command Pc when sent to 7 + 28, that is, generates a pressure control amount Pp such that the pressure Pf approaches and matches the pressure command Pc. Pressure command P
and a pressure error calculation unit 23 such as a subtraction circuit for calculating the difference ΔP by subtracting the pressure Pf from c.
A pressure control amount calculation unit 24 is also provided which generates a pressure control amount Pp by also performing appropriate processing such as amplification and integration on P.

In addition to the above, the motor controller 20 automatically switches from speed control to pressure control. In addition, the motor controller 20 can appropriately determine the switching even if there are no difficult-to-decide thresholds. Selection means 25 + 26 as follows
Is provided. That is, in order to select one of the speed control amount Vp and the pressure control amount Pp and supply it to the motor rotation control means 27 + 28, the difference means ΔV and the difference ΔP are input to the selection means 25 + 26 and the magnitudes thereof are compared. The speed control amount Vp is selected as the current command Ip when the difference ΔV is smaller than the difference ΔP based on the comparison unit 25 and the selection S obtained as a result of the comparison, and the pressure control is set as the current command Ip when the difference ΔV is larger than the difference ΔP. And a selection switching unit 26 for selecting the amount Pp and sending the current command Ip to the current control unit 27.

The motor rotation control means 27 + 28 receives the current command Ip from the selection switching section 26 and receives the drive current If from the current detection means 4a, and generates a control signal for matching the drive current If to the current command Ic. The current control unit 27 receives the control signal, performs appropriate processing such as pulse width modulation on the control signal, and performs three-phase pulse signals Up, Vp, W
and a pulse width modulation unit 28 (signal conversion means) for generating p. The three-phase pulse signals Up, Vp, Wp
Are sent to the motor driver 30.

Further, the motor controller 20 is also provided with a switching valve drive circuit 29 (switching operating means) for operating the switching valve 5b in accordance with the selection S of the selecting means 25 + 26. The switching valve drive circuit 29 is, for example, a relay circuit or a power transistor circuit suitable for exciting the electromagnetic drive unit of the switching valve 5b, and turns on / off the switching signal A in response to the selection S. . Specifically, when the selection S selects the speed control amount Vp as the current command Ip, the switching signal A is turned off and the pump displacement is switched to the upper limit of the displacement range by the displacement mechanism 5a as described above. When the pressure control amount Pp is selected as the current command Ip, the switching signal A is turned on, and the pump displacement is switched to the lower limit of the displacement range by the displacement control mechanism 5a.

The motor driver 30 includes a pair of series-connected transistors Q1 and Q2, one of which is turned on and the other is cut off in accordance with the pulse signal Up, and the pulse signal V
transistor pair Q3, which is turned on and off alternately according to p.
The inverter includes a transistor pair Q5 and a transistor pair Q5 and Q6 that are turned on and off alternately according to a pulse signal Wp. Each of the transistors Q1 to Q6 is composed of a power transistor such as an IGBT, and a flywheel diode, a snubber circuit (not shown) and the like are appropriately added as needed. The three transistor pairs are connected between a pair of positive and negative wires extending from a power supply unit 31 for converting a commercial alternating current into a direct current, and the positive side transistors Q1, Q3, Q5
Are turned on and in a conducting state, each phase U, V,
While current flows into W, negative transistors Q2 and Q2
When Q4 and Q6 are on and in a conducting state, current is drawn from each phase U, V, W of the electric motor 4. It should be noted that an amplifier that amplifies and generates a base current corresponding to the pulse signals Up, Vp, and Wp and a pair of transistors that are simultaneously turned on to cause a fault such as a short circuit between these transistors and the motor controller 20. A circuit 32 and the like for prevention are also provided.

The mode of use and operation of the bistable pump and hydraulic device of the first embodiment will be described.

A specific example is a case where the movable member of the operating section 6 moves forward at a high speed and then reaches the operation limit 6a and moves forward at a very low speed close to a stopped state. In response to this, the speed command Vc and the pressure command Pc start. It is assumed that the pressure command Pc is given as a positive constant value from time to forward movement and almost stop, and the pressure command Pc is larger than the speed command Vc.

Then, until the operation limit 6a is reached, the movable member of the operating section 6 advances smoothly and the pressure Pf does not increase, while the speed Vf follows the speed command Vc, so that the difference ΔV is smaller than the difference ΔP. Since the state is maintained, the speed control is selected by the selection S from the comparing unit 25, so that the speed control amount Vp from the first control amount calculating means 21 + 22 is used for the current command Ip, and the speed control causes the speed Vf Is maintained to follow the speed command Vc.

In this state, the switching signal A is turned off by the switching valve drive circuit 29 according to the selection S, and the switching valve 5b operated by this switches the capacity of the liquid pump 5 to the range of the variable capacity range by the variable capacity mechanism 5a. Since the upper limit is set, the discharge amount Q of the liquid pump 5 is increased together with the electric motor 4 being rotated at a high speed by the speed control.
It is maintained at an amount necessary and sufficient to move the movable member of the operating section 6 at the speed corresponding to the speed command Vc (see the solid line graph in FIG. 1B). Thus, the movable member of the operating section 6 advances at a substantially constant speed until it reaches the operation limit 6a. In addition, the entire discharge amount is supplied to the drive of the operating section without waste while exhibiting the pump discharge capacity to the maximum.

Then, the movable member of the operating section 6 has an operating limit 6a.
, A strong reaction force or the like is generated to stop the progress, and the pressure Pf rises rapidly while the speed Vf cannot follow the speed command Vc. Accordingly, the difference ΔP sharply decreases, the difference ΔV sharply increases, and the difference ΔP falls below the difference ΔV. Then, correspondingly, the content of the selection S from the comparing unit 25 is switched, and the pressure control is selected by the selection S. Therefore, the pressure control amount Pp from the second control amount calculating means 23 + 24 is used for the current command Ip. Then, the pressure control causes the pressure Pf to follow the pressure command Pc.

Further, at this time, the switching signal A is turned on by the switching valve drive circuit 29 according to the selection S, and the capacity of the liquid pump 5 is reduced to the lower limit of the capacity variable range by the capacity variable mechanism 5a by the switching valve 5b operated by this. Is done. At this time, the switching valve 5b is slowly switched by the action of the throttle 5k, and accordingly, the capacity of the liquid pump 5 also slowly changes from the upper limit to the lower limit of the variable capacity range by the variable capacity mechanism 5a. 20, the feedback control of the electric motor 4 by the operation of the switching valve 5b works without being temporarily disabled, so that the rotation speed of the electric motor 4 is adjusted to an appropriate rotation speed by the pressure control, and the liquid pump 5 The discharge amount Q of the liquid pump 5 is reduced without causing a shock, and the discharge pressure P is increased by advancing the movable member of the operating unit 6 at a low speed.
Settle down to the amount necessary and sufficient to maintain the pressure corresponding to c (see the long dashed line graph in FIG. 1B).

In this state, since the variation of the discharge flow rate Q is generally small, the rotation of the electric motor 4 is generally determined in inverse proportion to the capacity of the liquid pump 5. Therefore, when the motor rotation speed during the pressure control is too high and the mechanical efficiency of the electric motor 4 or the liquid pump 5 is not good, the contact position adjusting screw mechanism 5
The lower limit of the variable capacity range by the variable capacity mechanism 5a is increased by adjusting j. Then, if the motor rotation speed is the same, the discharge flow rate Q increases (see the short dashed line graph and the dotted line graph in FIG. 1B). However, the discharge flow rate Q is maintained at a required amount by feedback control. The motor rotation speed decreases.

As described above, the fluctuation of the pressure Pf is suppressed during the pressure control, and the fluctuation of the speed Vf is suppressed during the speed control, so that the control following the control commands Vc and Pc is accurately performed in any control state. Moreover, the main controller 1 sends a control command Vc,
It is sufficient to provide Pc, and it is not necessary to directly control the capacity of the liquid pump 5, so a simple one is sufficient. Also, the difference Δ
Since the switching determination is performed based on the magnitude comparison between V and ΔP, the automatic switching from speed control to force control is reliably performed without a predetermined threshold or the like.

Further, since the switching signal A is directly generated using the selection S generated at the time of the switching determination, the motor controller 20 which controls the displacement of the liquid pump 5 is generated.
Is also simple. As a result, a hydraulic device that performs speed control and force control in an operating state by varying the motor rotation speed and the pump displacement without complicating not only the pump structure but also the main controller 1 and the motor controller 20 is realized. In addition, energy efficiency can be improved.

[0047]

Second Embodiment A specific configuration of a second embodiment of the bistable pump and the hydraulic device according to the present invention will be described with reference to the drawings. 4A and 4B show the configuration of the hydraulic device, wherein FIG. 4A is an overall block diagram, and FIG. 4B is a block diagram of a part of a motor controller. 5A and 5B show a pump structure and the like, wherein FIG. 5A is a detailed block diagram, and FIG. 5B is a graph of pressure-flow rate characteristics.

This hydraulic device differs from that of the first embodiment in that the electric motor 4 is changed from a servo motor to an induction motor 41 of open control, and the motor controller 20 is used accordingly. This is the point that the motor controller 42 of FIG. The bistable pump 5 is different from that of the first embodiment in that an upper limit adjusting means 5m is added.

The induction motor 41 (see FIG. 4A)
An inexpensive general cage-type three-phase induction motor or the like is employed, and since the open control is performed, that is, the induction motor 41 itself and the feedback control with detection immediately before and after the induction motor 41 are not performed, the current detection means 4a is omitted. ing. However, since the feedback control other than the motor rotation control is not excluded, the liquid pump 5 and the operating part 6 provided at the tip of the induction motor 41 are provided with the speed detecting means 6b and the force detecting means 6c. The detection (Pf, V
The feedback control based on f) is also carried over to the motor controller 42.

The difference between the motor controller 42 and the motor controller 20 lies in the motor rotation control section. The current control section 27 and the pulse width modulation section 28 include a voltage control oscillation circuit (VCO) 43 and a three-phase conversion section. 44 has been replaced. That is, (see FIG. 4B), in the motor controller 42, following the selection switching unit 26,
A VCO 43 that receives a current command Ip as a control voltage and changes the oscillation frequency in accordance with the control voltage, and a three-phase converter 44 that generates three oscillation signals having phases shifted from each other from the oscillation signals and sends them to the motor driver 30 as an inverter. Is provided so that the rotation speed of the induction motor 41 can be varied without feedback of the drive current If.

The upper limit adjusting means 5m (see FIG. 5A)
As long as the contact end to the swash plate 5h can be advanced and retracted by an external operation similarly to the contact position adjusting screw mechanism 5j, either the same structure as the contact position adjusting screw mechanism 5j or a different structure. Although it is good, it is installed at a position where it comes into contact with the swash plate 5h from the side opposite to the contact position adjusting screw mechanism 5j, so that the upper limit of the capacity variable range by the capacity variable mechanism 5a can be adjusted from outside. (See the long dashed line graph, the short dashed line graph, and the dotted line graph in FIG. 5B).

In this case, since the rotation control of the induction motor 41 is an open control, the rotation speed of the induction motor 41 slightly fluctuates depending on the amount of slippage in the induction motor 41, but the detection (Pf, Vf )
Are absorbed by the feedback control of the motor controller 42 based on the above, and other operations and the like are almost the same as those described above in the first embodiment. Therefore, even with an inexpensive hydraulic device in which the servomotor is eliminated and the induction motor 41 is opened and controlled by the inverter 30, the motor rotation speed and the pump displacement can be varied without complicating not only the pump structure but also the control means. As a result, a hydraulic device that performs speed control and force control in the operating state can be realized, and improvement in energy efficiency can be achieved. Moreover, in this case, the variable capacity mechanism 5a
The upper limit as well as the lower limit of the variable capacity range can be adjusted, so that in addition to operating conditions during pressure control, operating conditions during speed control should be adapted to various operating environments and situations. It's getting easier.

[0053]

Third Embodiment A hydraulic apparatus according to the present invention whose flow chart is shown in FIG. 6 is a modification of the above-described first embodiment in another form. That is, a computer is used for the motor controller 20, and the first and second control amount calculation means, the selection means, the motor rotation control means, and the like are embodied by program processing. A general-purpose microprocessor, a digital signal processor, or the like is used for the computer, and a serial or parallel digital data input / output circuit is built in or externally attached. Also, A
A / D conversion circuit and a D / A conversion circuit are provided as necessary.

The processing will be described in detail. First, the speed command Vc, the speed Vf, the pressure command Pc, the pressure Pf, and the drive current If are converted into digital values and input (step S).
1) The difference ΔV and the difference ΔP are calculated from them (step S2). Next, the difference ΔV and the difference ΔP are compared (step S3), and when the difference ΔV is smaller than the difference ΔP, the difference ΔV
The speed control amount Vp is calculated from the integral value or the like before that and is set as the current command Ip (step S4), and the switching signal A is turned off (step S5). The pressure control amount Pp is calculated from ΔP and the integrated value before it, and is calculated as the current command Ip (step S6), and the switching signal A is turned on (step S7). Then, a drive current value that eliminates the difference between the current command Ip and the drive current If is calculated (step S8), and three-phase pulse signals Up, Vp, and Wp are generated by pulse width modulation processing based on the calculated value. It is sent to the motor driver 30 (step S9). The motor controller 20 is configured to repeat the series of processes at a predetermined cycle.

In this case, the processing of the speed error calculating section 21 and the pressure error calculating section 23 is performed in step S2, the processing of the comparing section 25 is performed in step S3, and the speed control amount calculating section 22 and the selection switching are performed in step S4. The processing of the unit 26 is performed,
In step S6, the pressure control amount calculation unit 24 and the selection switching unit 2
6, the output process to the switching valve drive circuit 29 is performed in steps S5 and S7, the process of the current control unit 27 is performed in step S8, and the process of the pulse width modulation unit 28 is performed in step S9. Therefore, the operation result is the first
This is the same as described in the embodiment.

[0056]

[Others] In the above embodiment, the case where the operating portion 6 is a hydraulic actuator such as a cylinder has been described. However, the application of the present invention is not limited thereto, and a hydraulic motor or another actuator may be used. For example, a combination of a rotation / linear motion conversion mechanism such as a ball screw and a pressurizing mechanism such as a ram cylinder, and a swing mechanism connected via a reduction gear or the like are often used. In addition, its application is, for example, in addition to a press device and a die cast machine, a glass forming machine,
It is possible in various fields, such as a machine tool, an injection molding machine, a press-fitting part mounting device, a transfer device, and a robot arm. Further, the liquid is widely used for hydraulic pressure and is easy to use.However, the liquid is not limited to the hydraulic pressure.For example, depending on the characteristics and restrictions of the application, water, a chemically synthesized liquid, and a mixed liquid of different kinds of liquids are used. Alternatively, a mixed liquid of powder and granules may be used.

Further, as for other components, the first detecting means includes the speed detecting means 6b described above.
In addition to the method for directly calculating the velocity Vf as described above, a method for measuring a physical quantity which is the basis of speed calculation such as acceleration and position can be used, or a flow meter or the like for measuring the discharge flow rate Q of the liquid pump 5 can be used. Can be. The detection of the pump discharge flow rate Q is not only a direct means for measuring the fluid volume, but also a means for measuring a differential pressure or a dynamic pressure in a flow path and converting it into a flow rate, or a method for measuring the capacity and the rotation speed of the liquid pump 5. It may be an indirect means such as one that measures and calculates the discharge flow rate Q. The capacity of the liquid pump 5 can be obtained, for example, by providing a tilt angle sensor with respect to the swash plate in the case of an axial piston pump. Even in such a case, the pump discharge flow rate Q is estimated because of high speed rotation during speed control. Since the error of the calculation result is small, an appropriate detection value can be obtained. The second detecting means includes:
In addition to a pressure gauge for detecting pressure, a type for detecting a force generated in the operating unit 6 in accordance with the discharge pressure P of the liquid pump 5 can be used, and an operating force or the like of the operating unit 6 is detected as the force Pf. In such a case, a load cell or the like is employed, and is attached to an operating member that generates a thrust, a member that receives the thrust, and the like.
When detecting torque, a torque meter or the like is also used.

Further, in addition to the above-described PI control, PID control, vector control, and the like are appropriately employed in the speed control amount operation unit 22 and the pressure control amount operation unit 24, and the method uses appropriate hardware and software. It is embodied by general design techniques. The VCO 43 and the three-phase converter 44 are not limited to analog circuits as described above, and may be based on digital counter circuits or computer program processing, and may involve pulse width modulation or the like. When the electric motor 4 is a servo motor, a permanent magnet synchronous motor or the like is used for a brushless DC servo motor, and a squirrel cage induction motor is frequently used for an induction motor.

In each of the above embodiments, the main controller 1 and the motor control electronic circuit 2 are separated into separate units. However, the present invention is not limited to this. The circuits 2 may be integrated in the same unit, or the main controller 1 and the motor controller 20 may be the same unit. Alternatively, they may be integrated into the same computer system. In such a case, the speed command Vc and the pressure command Pc are generated in the motor control electronic circuit 2 and transferred between boards, between circuit blocks, or between routines. There is also.

In each of the above embodiments, the liquid pump 5
Although the presence of a directional control valve, a relief valve, and the like in the liquid flow path from the to the operating unit 6 was not specified, the present invention does not deny the existence thereof, and the directional control valve and the like may be incorporated. good. Further, various hydraulic circuits or the like may be connected as appropriate for reciprocating motion of the movable member of the operating portion, ensuring safety, and the like, or as necessary.

[0061]

As is apparent from the above description, in the bistable pump and the hydraulic device according to the first solution of the present invention, the control conditions are narrowed down by switching the displacement of the bistable pump. This has the advantageous effect that a hydraulic device or the like for selectively performing speed control and force control in the operating state by varying the motor rotation speed and the pump capacity can be easily realized including the control means. There is.

Further, in the bistable pump and the hydraulic device according to the second solving means of the present invention, the switching of the pump capacity which is useful for narrowing down the control conditions is performed by the switching valve, so that the motor is improved. There is an advantageous effect that a hydraulic device or the like for selectively performing speed control and force control in an operating state by changing the rotation speed and the pump capacity can be realized more easily including the control means.

Further, in the bistable pump and the hydraulic device according to the third solution of the present invention, the lower limit of the variable capacity range can be adjusted to lower the rotational state of the electric motor or the liquid pump during force control. In this way, even when the motor speed and the pump displacement are varied to selectively perform the speed control and the force control in the operating state, a simple hydraulic device or the like including the control means can be used for the force control. This has an advantageous effect that the reduction in mechanical efficiency can be easily prevented.

Further, in the bistable pump and the hydraulic device according to the fourth solution of the present invention, the liquid supply state is prevented from suddenly changing beyond the acceleration / deceleration performance of the electric motor or the like. Therefore, even if the speed control and the force control in the operating state are selectively performed by changing the motor rotation speed and the pump displacement, the mechanical efficiency at the time of the force control is reduced in the simple hydraulic device including the control means. And it is possible to easily prevent the occurrence of an impact when switching from speed control to force control.

[Brief description of the drawings]

FIG. 1 shows a pump structure and the like of a first embodiment of a bistable pump and a hydraulic device of the present invention, (a) is a detailed block diagram, (b) is a graph of pressure-flow rate characteristics, and (c) is a graph. FIG. 3D is a perspective view of a main part showing the principle of a variable capacity system using a swash plate, and FIG.

2A and 2B show the structure of a hydraulic device, wherein FIG. 2A is an overall block diagram and FIG. 2B is a block diagram of a motor controller.

FIG. 3 is a circuit diagram of a motor driver.

4 (a) is an overall block diagram and FIG. 4 (b) is a block diagram of a part of a motor controller according to a second embodiment of the bistable pump and the hydraulic device of the present invention.

5A and 5B show a pump structure and the like, wherein FIG. 5A is a detailed block diagram, and FIG. 5B is a graph of pressure-flow rate characteristics.

FIG. 6 is a flowchart showing a processing procedure of a motor controller for a third embodiment of the bistable pump and the hydraulic device of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Main controller (sequence control means for application) 2 Electronic circuit for motor control (control driving device of electric motor) 4 Electric motor (servo motor) 4a Current detecting means (motor torque detecting means) 5 Liquid pump (variable displacement with switching valve) Type pump, bistable pump) 5a variable capacity mechanism (swash plate tilting mechanism) 5b switching valve (solenoid valve, switching means) 5i pressure guiding path (liquid flow path, communication path for guiding pilot pressure) 5j contact position adjusting screw Mechanism (stopper, lower limit adjusting means) 5k Throttle (orifice, choke, switching alleviation means) 6 Actuator (actuator such as hydraulic motor or cylinder unit) 6a Operation limit 6b Speed detecting means (speed sensor, flow sensor, first detecting means) 6c) Force detection means (pressure sensor, thrust sensor, second
Detection means) 20 motor controller (control circuit, electronic control unit for electric motor) 21 speed error calculation unit (flow rate / speed control means, first
Control amount calculation means) 22 speed control amount calculation unit (flow rate / speed control means, first control amount calculation means) 23 pressure error calculation unit (force control means, second control amount calculation means) 24 pressure control amount calculation unit (force Control means, second control amount calculation means) 25 comparison section (judgment means, selection means) 26 selection switching section (switch, selector, motor rotation control selection means) 27 current control section (motor torque control section, servo motor rotation control) Means) 28 pulse width modulation section (control signal conversion section, servo motor rotation control means) 29 switching valve drive circuit (AC / DC / solid state relay circuit, switching operation means) 30 motor driver (drive of inverter, power circuit, electric motor) 41) Induction motor (open control electric motor) 42 Motor controller (control circuit, electronic control unit for electric motor) 43 VCO (voltage control) Oscillation, motor rotation control means) 44 three-phase conversion portion of the open control (control signal conversion unit, open the motor rotation control means)

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) F15B 11/00 F15B 11/00 F 11/02 11/02 C (72) Inventor Kazuyuki Kihara 2 Minami Kamata, Ota-ku, Tokyo No. 16-46 F-term in Tokimec Co., Ltd. (reference) DA14 DB43 EE39 FF06 FF07 GG01 JJ20

Claims (5)

[Claims] 1. A bistable pump according to claim 1, wherein said variable displacement liquid pump is provided with a switching means for switching a pump displacement to either an upper limit or a lower limit of a variable displacement range. 2. A pump main body, which is driven to rotate and sucks and discharges a liquid, a capacity variable mechanism for changing a discharge capacity per unit rotation thereof, and a pressure guide passage communicating with a pressure receiving portion of the variable capacity mechanism. A bistable pump having a switching valve connected to connect a high-pressure side flow path such as a discharge pressure and a low-pressure side flow path such as a suction pressure. 3. The bistable according to claim 1, further comprising lower limit adjusting means for adjusting a lower limit of the variable capacity range or a lower limit of the variable capacity range by the variable capacity mechanism. pump. 4. A bistable pump according to claim 3, further comprising a switching mitigation means for lowering a switching speed when said switching means or said switching valve switches said variable capacity range from an upper limit to a lower limit. . 5. The bistable pump according to claim 1, an electric motor for driving the pump, an operating unit receiving a supply of pressure liquid from the bistable pump, and the bistable pump. First detection means for detecting a discharge flow rate of a pump or a physical quantity corresponding to the speed of the movable member of the operating unit corresponding thereto, and the first control command received or generated in response to the first control command.
A first control amount calculating means for generating a first control amount for following the detection value of the detecting means; a second detecting means for detecting a discharge pressure of the liquid pump or a force generated in the operating portion in response thereto; A second control amount for generating a second control amount for causing a detection value of the second detection means to follow a second control command generated or generated;
Control amount calculating means, selecting means for selecting one of the first control amount and the second control amount and providing rotation control of the electric motor, and the switching means or the switching means corresponding to the selection. A hydraulic device comprising: a switching operating means for operating a valve.